KR101301515B1 - LCD with color-filter on TFT and method of fabricating of the same - Google Patents

Abstract

The present invention relates to a liquid crystal display device, and a liquid crystal display device having a COT structure in which a color filter is formed on an array substrate.

Particularly, in order to minimize the alignment margin required for bonding the lower substrate and the upper substrate including the color filter, the bonding key is formed around the upper substrate, and the alignment key is an alignment layer. In the process of forming a process is carried out at the same time.

Doing so, phase. In the process of bonding the lower substrate, there is an advantage of minimizing the bonding margin and further increasing the liquid crystal margin.

Description

CIO structure liquid crystal display and manufacturing method thereof {LCD with color-filter on TFT and method of fabricating of the same}             

1 is an exploded perspective view schematically showing a configuration of a general liquid crystal display device,

2 is a cross-sectional view schematically illustrating a configuration of a conventional liquid crystal display (COT) structure.

3 is a first cross-sectional view schematically illustrating a configuration of a COT structure liquid crystal display device according to the present invention;

4 is a second cross-sectional view showing the configuration of a COT structure liquid crystal display device according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

200: first substrate 202: first bonding key

250: second substrate 252: common electrode

254: alignment layer 256: second bonding key

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a color filter on TFT (COT) structure and a method of manufacturing the same.

In general, a liquid crystal display device displays an image by using optical anisotropy and birefringence characteristics of liquid crystal molecules. When an electric field is applied, the alignment of liquid crystals is changed, and the characteristics of light transmission vary according to the arrangement direction of the changed liquid crystals.

In general, a liquid crystal display device is formed by arranging two substrates on which electric field generating electrodes are formed so as to face the surfaces on which two electrodes are formed, injecting a liquid crystal material between the two substrates, and then applying voltage to the two electrodes. By moving the liquid crystal molecules by the electric field is a device that represents the image by the transmittance of light that varies accordingly.

1 is a view schematically showing a liquid crystal display according to the related art.

As shown, a general color liquid crystal display 11 includes a color filter 7 and a color filter 7 including a black matrix 6 formed between a sub color filter 8 and each sub color filter 8. The upper substrate 5 having the common electrode 18 deposited thereon, the pixel region P, and the pixel electrode 17 and the switching element T formed in the pixel region, and the pixel region P The liquid crystal 14 is filled between the lower substrate 22 and the upper substrate 5 and the lower substrate 22 on which array wiring is formed.                         

The lower substrate 22 is also referred to as an array substrate, and the thin film transistor T, which is a switching element, is positioned in a matrix type, and the gate wiring 13 crosses the plurality of thin film transistors TFT. ) And data wirings 15 are formed.

In this case, the pixel area P is an area defined by the gate line 13 and the data line 15 crossing each other, and a transparent pixel electrode 17 is formed on the pixel area P as described above.

The pixel electrode 17 uses a transparent conductive metal having a relatively high transmittance of light, such as indium-tin-oxide (ITO).

A storage capacitor C connected in parallel with the pixel electrode 17 is formed on the gate wiring 13, and a part of the gate wiring 13 is used as the first electrode of the storage capacitor C, and a second As an electrode, an island-shaped source / drain metal layer 30 formed of the same material as the source and drain electrodes is used.

In this case, the source / drain metal layer 30 may be in contact with the pixel electrode 17 to receive a signal of the pixel electrode.

However, as described above, when the upper color filter substrate 5 and the lower array substrate 22 are bonded to each other to produce a liquid crystal panel, light leakage due to the bonding error between the color filter substrate 5 and the array substrate 22 is poor. There is a very high probability of occurrence.

Therefore, in order to solve this problem, a COT (color filter on TFT) structure for constructing a color filter on an array substrate has recently been proposed.                         

2 is an enlarged cross-sectional view schematically illustrating a configuration of a liquid crystal display device having a COT structure according to the related art.

As shown in the drawing, the liquid crystal display device 100 having the COT structure according to the related art is composed of an array substrate 110 and an upper substrate 150 which is bonded to the array substrate 110 through a sealant 180.

The array substrate 110 includes a thin film transistor T including a gate electrode 112, an active layer 120, a source electrode 122, and a drain electrode 124 on a substrate surface, but is not illustrated. A gate line and a data line 114 (not shown) are formed to vertically intersect the transistor T to define the pixel region P. Referring to FIG.

A gate pad 116 is configured at one end of the gate wiring 114, and a data pad (not shown) is configured at one end of the data wiring (not shown).

Red, green, and blue color filters 128a, 128b (not shown) and a black matrix 130 are formed on the front surface of the substrate 110 having the thin film transistor T and the array wiring, and the color filters 128a and 128b. , Not shown, is configured to correspond to the pixel region P, and the black matrix 130 is configured to correspond to the channel region CH of the thin film transistor T.

A transparent pixel electrode 134 is formed on the red, green, and blue color filters 128a and 128b (not shown) to contact the drain electrode 124.

The first alignment layer 136 is formed by applying polyimide on the pixel electrode 134 described above.

The common electrode 152 is formed on one surface of the upper substrate 150 corresponding to the array substrate 110 configured as described above, and the second alignment layer 154 is formed on the common electrode.

In the above-described configuration, in the case of poor adhesion during the process of bonding the first substrate 110 and the second substrate 150 through the sealant 180, when the sealant 180 comes into contact with the alignment layer 154 or 136, Poor failure may occur.

Therefore, the sealant 180 and the alignment layer should be configured with a sufficient separation distance (S1). In this case, the separation distance includes a process margin, and the first substrate 110 and the second substrate 150 by the included margin. Since the amount of liquid crystal injected between the two increases, the liquid crystal margin (LC margin) is increased to reduce the competitiveness of the product in terms of cost.

The present invention has been proposed for the purpose of solving the above problems,

The present invention is characterized in that the bonding key is formed simultaneously around the substrate in the PI process of forming the alignment layer on the upper substrate for the COT structure liquid crystal display.

In this way, since the distance between the edge of the alignment layer and the sealant can be minimized, an increase in the liquid crystal margin can be prevented and a poor adhesion can be prevented.

According to an aspect of the present invention, there is provided a method of manufacturing a COT (COT) structure liquid crystal display device, comprising: preparing a first substrate and a second substrate; Forming gate lines and data lines on one surface of the first substrate facing the second substrate so as to perpendicularly cross each other to define a pixel area; Forming a switching element at an intersection point of the gate line and the data line; Forming a color filter in the pixel region; Forming a transparent pixel electrode on the color filter, the transparent pixel electrode in contact with the switching element; Forming a first alignment layer on the first substrate including the pixel electrode; Forming a common electrode on one surface of the second substrate facing the first substrate; Forming a second alignment layer on the common electrode; Melting a portion of the surface of the second substrate at an outer side of the second substrate to form a bonding key.

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Forming a bonding key on one surface of the first substrate corresponding to the bonding key formed on the second substrate, the bonding key being made of the same material as the gate wiring or the data wiring; Is removed after the process is complete.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

Example

3 is a cross-sectional view schematically showing the configuration of a COT structure liquid crystal display device according to the present invention.

As illustrated, the COT structure liquid crystal display device LP is formed by bonding the first substrate 200 and the second substrate 250 to each other with a liquid crystal (not shown) therebetween.

The first substrate 200 includes a thin film transistor array unit AP including a color filter, and a first bonding key 202 around the first substrate 200.

In this case, the first bonding key 202 may be formed of the same material in the process of forming the electrode and the wiring during the process of forming the thin film transistor array part AP.

The common electrode 252 and the alignment layer 254 are formed on one surface of the second substrate 205 facing the first substrate 200.                     

When the alignment film 254 is configured by a printing method, a bonding key shape pattern is further formed on a printing plate on which the alignment film 254 is printed, and at the same time as the step of forming the alignment film, The second engaging key 256 can be configured.

In this case, a colored resin may be used as the second bonding key 256. That is, the alignment plate 254 and the colored resin are applied to the printing plate, and then the printing method may be used.

In addition, the bonding key may be formed by dropping and aligning the alignment layer on the portion where the bonding key 256 is to be formed using an ink jet method.

As described above, in addition to forming a bonding key using a resin including an alignment layer and a pigment, the bonding key may be marked by melting a portion of the glass by irradiating a laser beam.

Hereinafter, with reference to FIG. 4, the configuration of the liquid crystal display device having the COT structure including the above-described bonding key will be described.

4 is a cross-sectional view schematically showing the configuration of a C0T structure liquid crystal display device according to the present invention.

In the COT structure liquid crystal display (LP) according to the present invention, the upper substrate 350 and the lower substrate 300 defined by the display area DA where an image is actually displayed and the non-display area NDA surrounding the display area are bonded together. To configure.

The display area DA is composed of hundreds of thousands to millions of pixels P according to the size and resolution of the liquid crystal display device LP.                     

A gate wiring 304 is formed in one direction for each pixel P in the lower substrate 300, and a data wiring (not shown) is formed in a direction perpendicular thereto, and the gate wiring 304 and the data wiring ( A thin film transistor T is formed at each intersection portion of the thin film transistor T, and the thin film transistor T includes a gate electrode 302, an active layer 320, a source electrode 322, and a drain electrode 324. .

A gate pad 306 is formed at the end of the gate line 304, and a data pad is not formed at the end of the data line (not shown).

Red, green, and blue color filters 328a, 328b (not shown) are sequentially formed in the plurality of pixels P, and the black matrix 320 is configured to correspond to the thin film transistor T.

An upper portion of the color filters 328a and 328b (not shown) may be independently patterned for each pixel P to form the pixel electrode 334, and the pixel electrode 334 may be in contact with the drain electrode 324. The pixel voltage is input from the drain electrode 324.

The passivation layer PL and the first alignment layer 336 are formed on the entire surface of the substrate 300 including the source and drain electrodes 322 and 324.

In the above-described configuration, the first bonding key 400 may be formed in the process of forming each electrode and the wiring constituting the thin film transistor T.

An alignment key 356 is formed at the same time as the common electrode on the upper substrate 350 corresponding to the lower substrate 300 configured as described above, and the second alignment layer 354 on the common electrode 352. .

When the second alignment layer 354 is formed by a printing method, the substrate 300 may be formed at the same time as the step of forming a second alignment layer by further forming a bonding key shape pattern on a printing plate on which the second alignment layer 354 is printed. The second bonding key 356 of the desired shape can be configured on the outside of the.

In this case, a colored resin as well as an alignment layer may be used for the second bonding key 356. That is, the second alignment layer 354 and the colored resin may be applied to a printing plate, and then the printing method may be used.

In addition, by using an ink jet method, the bonding key may be formed by dropping and solidifying the alignment material on the portion where the bonding key 356 is to be formed. In addition to the alignment material, colored ink may be dropped to form the bonding key 356.

In addition to the method of forming the bonding key using the alignment material as described above, the bonding key may be marked by a process of melting part of the glass by irradiating a laser beam.

In the bonding process, the upper substrate 350 and the lower substrate 300 accurately align the first bonding key 400 and the second bonding key 356 by using a CCD camera and then perform the bonding process. In this case, the separation distance S2 between the sealant 380 and the alignment layers 354 and 346 may be minimized.

After the bonding process is completed, a portion of the upper substrate on which the bonding key 356 is formed is removed to expose the gate pad electrode and the data pad electrode 306 (not shown).

Hereinafter, the manufacturing process of the lower substrate will be described step by step.                     

First step: After the gate wiring 304 and the gate electrode 302 are formed on the substrate 300, a gate insulating layer GI is formed on the entire surface of the substrate 300.

Second Step: An active layer 320 and an ohmic contact layer OC are formed on the gate insulating layer GI corresponding to the gate electrode 302.

In this case, the active layer 320 is formed of amorphous silicon (a-Si: H), and the ohmic contact layer OC is formed of amorphous silicon (n + or p + a-Si: H) containing impurities.

The third step: forming a source electrode 322 and a drain electrode 324 spaced apart from the ohmic contact layer OC, and a data line (not shown) in contact with the source electrode 322.

The fourth step: depositing one selected from the group of inorganic insulating materials including silicon nitride (SiN _X ) and silicon oxide (SiO ₂ ) on the entire surface of the substrate 300 on which the source and drain electrodes 322 and 324 are formed. To form.

Fifth step: color filters 328a and 328b are formed, and a black matrix 330 is formed.

Sixth Step: The planarization layer PL is formed on the entire surface of the substrate 300 on which the black matrix 330 is formed.

The planarization layer PL is formed by coating one selected from a group of transparent organic materials including benzocyclobutene (BCB) and an acrylic resin.

The seventh step: the pixel electrode 334 is formed on the planarization film PL corresponding to the color filters 328a and 328b, and the alignment layer 336 is formed on the pixel electrode 334.                     

In the above-described steps, a lower substrate which is an array substrate including a color filter may be formed.

The COT structure liquid crystal display device formed as described above may minimize the distance (S2) between the sealant and the edge of the alignment layer in the process of bonding the upper substrate and the lower substrate through the sealant, thereby minimizing the liquid crystal margin. There is an advantage.

The COT liquid crystal display according to the present invention manufactured as described above may minimize the distance between the sealant and the edge of the alignment layer in the process of bonding the upper substrate and the lower substrate through the sealant, thereby minimizing the liquid crystal margin. There is an effect, and this effect can reduce costs, thereby improving the competitiveness of the product.

Claims (13)

delete delete delete delete delete delete delete delete delete delete Preparing a first substrate and a second substrate; Forming gate lines and data lines on one surface of the first substrate facing the second substrate so as to perpendicularly cross each other to define a pixel area; Forming a switching element at an intersection point of the gate line and the data line; Forming a color filter in the pixel region; Forming a transparent pixel electrode on the color filter, the transparent pixel electrode in contact with the switching element; Forming a first alignment layer on the first substrate including the pixel electrode; Forming a common electrode on one surface of the second substrate facing the first substrate; Forming a second alignment layer on the common electrode; Irradiating a laser beam from the outside of the second substrate to melt a portion of the surface of the second substrate to form a first bonding key And a second substrate of the portion where the first bonding key is formed is removed after the process is completed. The method of claim 11, Forming a second bonding key with the same material on one surface of the first substrate corresponding to the first bonding key formed on the second substrate, on the same layer on which the gate wiring or the data wiring is formed. (COT) Structure Liquid crystal display device manufacturing method. delete

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